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Well I know that there a lot of threads regarding this and I did do a search and could not find what I am looking for. I am in the market for a high flow cat and have narrowed it down to solo, however I am also looking for a good price and see that Performance Autowerks is having a sale and also have a high flow cat. What I couldn't find was anybody posting comments on the werks hfc,au contraire about the solo hfc, which has lots of positive feedback. So my question is what is the difference between these two makes? Will the werks throw codes? does it come with an o2 extender? solo converter length is 5", any body know how long the werks cat is? does anybody have any opinions on which high flow cat I should get , including other brands(magnaflow, etc)? Thanks in advance
Bert
 

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What are you after? More noise? Either one should do fine. More power? Then you will need a tune to go with the CAT, whether GMPP or otherwise.

I have the Solo CAT and GMPP tune and can attest to the high quality of the Solo products in general.
 

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What are you after? More noise? Either one should do fine. More power? Then you will need a tune to go with the CAT, whether GMPP or otherwise.

I have the Solo CAT and GMPP tune and can attest to the high quality of the Solo products in general.
Ditto for me on the Solo cat and GMPP tune. I love them!!!!:thumbs:
 

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What's wrong with more noise and more power? heheh! I will be getting the GMPP tune and Magnaflow exhaust. Time to wake this baby up!
 

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What's wrong with more noise and more power? heheh! I will be getting the GMPP tune and Magnaflow exhaust. Time to wake this baby up!
Might want to consider getting the Solo CAT and the Solo exhaust. Unlike the Magnaflow (which is decent quality but not up to the level of the Solo products) it necks down at the flange and isn't a true 3" system.
 

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What are you after? More noise? Either one should do fine. More power? Then you will need a tune to go with the CAT, whether GMPP or otherwise.

I have the Solo CAT and GMPP tune and can attest to the high quality of the Solo products in general.
Ditto for me on the Solo cat and GMPP tune. I love them!!!!:thumbs:
If all you have are the GMPP tunes and the high flow cat you make absolutely no more power than you would without the high flow cat due to the "learn down" nature of the GMPP tune.

The GMPP tune calls for a set amount of torque by calling for a set amount of air to be ingested for a given rate of fuel. And once you make the system more efficient, the tune detects this, and actually readjusts itself back down to the original power it was designed to make.

Unless you go with a "real" tune, don't bother getting any other power adders like high flow cats.:thumbs:
 

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I don't know where you are getting your info,but the GMPP tune does in fact allow for added benefits of after market parts if they provide a benefit. The GMPP tune adds about 30 HP and takes the torque from about 260 to around 340 for a 5 speed GXP The factory tune, without the GMPP tune will maintain 260 FT LBS and negate any benefits of after market part
 

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The info that came with my GMPP states that it shuts the learn down feature off. The dealer even said that it would run better after some aggressive driving and given it a chance to re set itself.
 

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There are a couple of interesting threads on this back just before and after the GMPP tune was first made available.

Bottom line is that the GMPP tune info said that it removed the learn down "feature". Then based on some fascinating info coming via various means from Westers, the GMPP does not really remove the "learn down". What it does is establish a new baseline that is ~340 ft pounds and results in about 290 HP. The "learn down" part of the code is not really learn down. In fact the code operates to maintain 1) 260 ft pounds of torque and 2) take care of the turbo by predicting its behavior and precluding over temp or over RPM. The end result is that when an owner modified the car to make more power, the baseline code would figure out that it was making over 260 ft pounds and would adjust such that it was making 260 ft pounds. This was interpreted as learning down but in fact the ECM software was just following its programming by making adjustments such that it was back to 260 ft pounds.

The GMPP updates the software by setting the target torque to be 340 ft pounds. It still protects the turbo from temp and / or speed. In addition, the GMPP tune sets the torque limits ABOVE the 340 ft pounds that it provides with the stock parts and the GMPP software. That means that if you add a high flow cat, the upper torque limits of the GMPP software will NOT force the engine down to the 340 ft pounds baseline. It will allow it instead to go up to take advantage of the high flow cats benefits. There is STILL a limit on torque, but it is higher than the 340 that the GMPP provides with the stock parts. My car was measured at about 400 ft pounds on the DDM dyno. The GMPP software does have an upper limit and it WILL learn down if you can figure out how to get enough parts on it to exceed the GMPP tune upper torque limit.

Hope this helps:yesnod::)
 

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I have the Magnaflow Catback and Trifecta Budget tune. The exhaust sounds great even with the stock cat but I am also looking at upgrading to catless or a high flow cat downpipe. It's true the Magnaflow has a neck down flang but I think Solo carries a flang that can be mated to the Magnaflow to make it a true 3". The Solo Cat will mate to the stock exhaust as well so there are no issue just installing the Solo HFC to the Magnaflow but the bottle neck with prevent some flow. Still love the way the Magnaflow sounds though.:thumbs:
 

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I don't know where you are getting your info,but the GMPP tune does in fact allow for added benefits of after market parts if they provide a benefit. The GMPP tune adds about 30 HP and takes the torque from about 260 to around 340 for a 5 speed GXP The factory tune, without the GMPP tune will maintain 260 FT LBS and negate any benefits of after market part
As far as I am aware, and there is a lot more information out there saying the GMPP tune learns down then there is that it does not, so let me ask you, where are you getting your info that the GMPP tune does not learn down?

The GMPP tune calls for a higher torque power out put then stock, and if you upgrade the mechanicals, it will continue to call for the same amount of torque.

Secondly, the GMPP tune is known to run unnecessarily lean under load, and with far too much knock to be safe, and to get the most performance out of the engine. That much knock on the GMPP tune only serves to cause knock retard, which then loses power again.

But anyways, I'm getting off topic. Here's where I have read that the GMPP tune learns down:

http://www.solsticeforum.com/forum/f63/going-gmpp-tune-trifecta-worth-cost-72411/

http://www.solsticeforum.com/forum/f63/can-someone-explain-gmpp-hp-tuners-thing-me-72300/
 

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Rob is correct about the GMPP not learning down, but also correct that there are other limitations not involving learn down that still apply - the air load moving through the engine is limited and if the turbo tries to move more than a target amount, the GMPP will limit it.

That's why a big wheel turbo gives no benefit in conjunction with the GMPP tune.

An explanation I received when investigating the big wheel mod was:

See, how our ECMS work is we have a table called the desired air load, well, when we tune this table, we tune it to what we want the car to put out for manifold pressure (or approximate pressure). The higher the number, the higher the pressure. The GM stage tune is going to command a set pressure like (for example, and example only because I do not know the stage tune off hand) 255kpa. 255kpa should net around 20 psi. Well, when you put a more efficient turbo on there, its still looking for that 255kpa, and thats it. So, say (again, example) the big wheel can push 255 kpa at 18 psi, the car will command the turbo to operate at 18psi and thats all.
 

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Discussion Starter #13
Both are good I have the SOLO cat and runs great with or without a tune. Tune just make it better. Had it since 2007 and work great and service is top notch will always be there for you.

FYI guys his question was about the Cat not a tune. Lets not confuse him on this thread and instead refer him to another thread as stated on what to do after a cat.
Have you tried the Werks or know the specs on Werks Cat? I have yet to contact Werks Directly and was hoping they would chime in and answer my questions so it would be clear to all on respects to the length/o2 extender/codes,etc, as their discription on their site does not address these.I'm not exactly sure how you can say they are both good, I have yet to talk with somebody(including yourself) that actually has one.As far as my original post,yes my qustion was about high flow cats, but please do not presume that I will get confused with related mods, perhaps it is you that is getting confused.It really is preference in regards to the different combos of Tune/HFC/exhaust one decides to get.I am debating Trifecta over GMPP, but at this point maintaining warranty is prevalent.That might change when I go to actually purchase. I appreciate all the responses and hope they continue.I do know that Whatever I get my permagrin will get bigger. And one last note to wspohn, I have read several times that 2.5" exhaust is sufficient until you do turbo upgrades, and that it is the stock cat that is the restrictor to the stock motor.
 

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I just put one on from Dave and Werks, it sounds great and you get a few more ponies. Call him, he is having a sale.
 

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I just took advantage of the werks sale. They said they do include the o2 extender piece, which should keep it from throwing codes.
 
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